Heretofore belt conveyors have been used for mass transport of articles such as cans through ovens such as for the purpose of drying or curing coatings applied to the cans. Known conveyor belts include spiral woven belts, rod reinforced belts, chain driven belts and flat wire belts. Being continuous, the belts have a carrier flight for transport of product and a return flight. Stationary type or roller type supports may be provided for the carrier flight to support the weight of the articles being conveyed as well as the weight of the carrier flight of the belt.
In the past a problem arose when using a stationary support in an oven for curing coatings on cans. The dragging of a metal conveyor belt, such as a flat wire belt, over the stationary support, such as slide bars, produced metal and ceramic fines that were objectionable to some users of these belt conveyors. One solution to this problem was obtained by using a roller bed to support the flat wire belt. This solution, however, was viewed by some as undesirable because of unsupported areas between rolls and wear due to belt abrasion.
Also known are tandem belt conveyors which use a primary conveyor belt and a support conveyor belt. A spiral woven belt has been used as the primary conveyor belt and a chain driven cross bar conveyor belt, including a pair of chains interconnected by transverse cross bars of circular cross-section, has been used as the support conveyor belt The two conveyor belts were mechanically linked whereby one conveyor belt was driven by the other for synchronous operation. This design, however, has several drawbacks including belt tracking and stretching problems. The conveyor belts may also lose synchronism as they wear and this may result in increased wear and production of metal fines because of the relative movement that arises from the belts moving at different speeds.
Still another known conveyor design uses a composite conveyor belt including a spiral woven belt and a chain driven cross bar conveyor belt. The cross bar conveyor belt includes a pair of chains interconnected by transverse cross bars of rectangular cross-section. In this design hold down clips are used to lock the spiral woven belt to the cross bars thereby to form a composite belt that is driven by a single drive.